I use emClient to aggregate emails from several Gmail accounts. Recently I figured I needed a rule but when I open the dialog, I get the message “Server files cannot be obtained nor changed because the selected account if offline.” Surely, I can have rules associated with a gmail account.
You can’t edit the server signature if there is no connection to the server.
Check you have an Internet connection and can send and receive using that account. Then try edit the signature again.
So, for anyone else having this problem I was able to get it working by sending myself an email from another device. It was received fine and then I was able to access rules. Perhaps simply emailing someone would also have worked. I don’t know how long the connection exists from your last email transaction but at least that worked.